is one piece episode 540 filler?

Jinbe decides to tell the others and Nami about how Fisher Tiger and Otohime tried to change Fish-Man Island. The story now goes back 16 years ago, on Fish-Man Island, a robber has taken some money with a hostage, then the Queen rushes over to help despite her guards saying they'll handle it.

The robber warns her and shoots, but Otohime dodges with the usage of Kenbunshoku Haki and slaps the robber. She screams in pain from the slap due to her fragile body.